In recent years, various elements in a field of light emitting devices/media and light processing device/media using minute fine particles/ultra fine particles have been studied. In order to apply such fine particles to various elements, high density integration obtained by depositing films or layers that include fine particle material on a solid substrate becomes a key factor. For example, thin films formed of highly integrated fine particles have been reported.
Thin films of inorganic compounds having desirable orientation can be formed with known methods, such as a molecular beam epitaxy method (MBE), a cluster ion beam method, an ion beam irradiation vacuum deposition method, a chemical vapor deposition method (CVD), a physical vapor deposition method (PVD), and a liquid phase epitaxy method (LPE). Thin films of organic compounds can be formed with known methods, such as a Langmuir Blow jet method (LB method). In general, dot particles may be obtained by allowing materials sublimed in high vacuum with a vacuum apparatus (e.g., MBE method) to form particles on a solid substrate in a self-organized manner.
The foregoing methods, however, have difficulty in controlling space between dot particles or size distribution of dot particles, and require greater cost for obtaining desired dot particles.
In view of such drawback, a liquid jet methods that is, a technique of forming a film of a material including fine particles by using liquid jet head are being proposed. For example, in one related art, an emulsion including nanoparticles is coated on a solid substrate by an inkjet coating technique, to form a thin film formed of ultra fine particles (nanoparticles) on the solid substrate.
Other than such liquid jet method, some conventional known methods for fabricating a circuit board are described below:
(1) A method of forming a copper wiring pattern has been proposed in which the copper wiring pattern is formed where a copper-clad laminate is covered with resist, is then exposed to form a circuit pattern with a photolithographic method, is then dissolved to remove unexposed resist, and is then etched at its resist-removed portions.
(2) In addition, a method of forming a conductive pattern has been proposed in which the conductive pattern is formed where a ceramic substrate is applied with a conductive paste for printing a desired circuit pattern by using a screen printing technique, and is then thermally processed in a nonoxide atmosphere for sintering metal fine particles in the conductive paste.
(3) Further, a method of forming a copper wiring pattern has been proposed in which the copper wiring pattern is formed where an insulating substrate, being formed with a thin conductive layer by deposition of conductive metal, is covered with resist, is then exposed to form a circuit pattern with a photolithographic method, is then dissolved for removing unexposed resist, and is then etched at its resist-removed portions.
Nevertheless, the foregoing conventional known methods may not be suited for forming fine patterns. Therefore, a method of forming fine patterns employing inkjet techniques has been proposed. In one exemplary method, a wiring patterns or a circuit board is fabricated by an inkjet method, in which a circuit pattern is directly drawn onto a substrate by applying metal paste. This method may simplify a fabrication process of fine patterns, have no necessity of waste fluid disposal, and require less manufacturing cost.
Although various methods using inkjet method have been proposed as above mentioned, there remains a need for improved methods of applying inkjet techniques for forming various devices and substrate patterns.